Advice on drainage for a dirt floor barn sunken below ground-level

Hi everyone,

We've just finished putting a new roof on our ruin, which is now ready to start being used as a goat barn and hayloft. We are located in the mountains of Portugal and this building is a traditional structure, constructed entirely of large granite stones.

My issue is that when you enter the barn, you step down from ground level onto a dirt floor that is between half a foot and one foot lower than ground level. I intend to build a mezzanine inside the barn so that it has two floors to maximise space as it is not large. However once the mezzanine is built, depending on how tall we make it, there will either not be enough room to stand underneath, or not enough room to stand on top. Neither is ideal as both of these areas will be accessible to the goats and will need regular cleaning, etc.

If I build it so that myself and my 6'2" partner can comfortably stand on top of the mezzanine, then we will have to crouch to get underneath it - however I thought because it's a dirt floor underneath that maybe we could dig it down a bit deeper.

I'm not sure how to check how far the walls go down into the ground and I was worried about undermining them.

I'm also concerned that when it rains heavily in winter, the ground floor could be flooded (regardless of whether we dig it down deeper or not!) The doors will need to be open most of the time to allow for airflow and access for the animals to go in and out. They currently have no thresholds (although this is something we might be able to add.

I thought about possibly digging a drainage ditch around the outside (French drain style?), but there is currently a wide concrete/cobbled path all around the outside which I would also like to retain if possible as we are on a tight budget and we don't really want to destroy it to dig a ditch then remake it afterwards. Would be willing to compromise and just get rid of it and dig the ditch if really necessary though.

I'd also like to keep the dirt floor rather than put concrete in as I've found that the deep litter method which we like to use for the goats really only works best for me on a dirt floor. However I am open to other suggestions (gravel? sand?)

I've attached a diagram of the structure. Blue line is supposed to show the mezzanine.

My current thinking is to dig it down deep enough that we can stand under the mezzanine and maybe just dig deep a pit in the floor and fill that with gravel and try to camber the rest of the floor gently towards the central pit. Would this work or would it just end up being a well of goat urine?

Any suggestions or possible compromises most welcome.

Interesting problem Rudyard....What is the general land level like around the barn? Is it flat, or some slope? If sloped then you may be able to make an interceptory ditch to divert substantial rain away from the barn.
Personally if keeping animals I would try and make it as easy as possible to get the shit soiled bedding out of the barn, so a sump does not seem a good idea to me, unless it could be washed out easily: ie above doorsill height. In effect you are looking to make a basement level in the barn. Would it be easier to go up instead? Make a timber structure on top of the walls, and raise the roof to give you more height.
I would make a small excavation to check the barn foundations for depth. Sometimes they can be a lot deeper than is apparent from current soil level as animals and plants have built up layers over the years. Our stone house has very shallow foundations however, although it is built on rock so not a problem structurally, it means a root cellar here is out of the question!

I'm going to throw a few ideas and maybe some will either stick, or generate even better ideas:

1. What is the slope of the roof? Could you build a mezzanine level across only at the tallest part of the roof, as a compromise?

2. Do you need a continuous mezzanine? Could you build sections of mezzanine, with gaps, so while clearing the bedding, you can be standing in a open area, but be reaching into a low area?

3. Considering your concern about undermining the foundation, have you considered digging out the floor further, but leaving 2 ft or so at its current depth all around the edge? Consider some kind of shoring (rock, old breeze blocks or a rot-resistant wood come to mind), to make sure the edge doesn't collapse over time. Again, the main part of the floor will be closer to head height, but you can reach with tools the area that is raised.

4. The step down is already considerable for humans. If you're going to be cleaning this out with a wheelbarrow, I would consider making a ramp in. At the very least, I would  be thinking hard about how to access both levels safely and for the things you need to use them for. Ramps take up a lot of space, so stairs might be better so long as you put a block and tackle in to raise and lower loads of things.

Nancy Reading wrote:Interesting problem Rudyard....What is the general land level like around the barn? Is it flat, or some slope? If sloped then you may be able to make an interceptory ditch to divert substantial rain away from the barn.
Personally if keeping animals I would try and make it as easy as possible to get the shit soiled bedding out of the barn, so a sump does not seem a good idea to me, unless it could be washed out easily: ie above doorsill height. In effect you are looking to make a basement level in the barn. Would it be easier to go up instead? Make a timber structure on top of the walls, and raise the roof to give you more height.
I would make a small excavation to check the barn foundations for depth. Sometimes they can be a lot deeper than is apparent from current soil level as animals and plants have built up layers over the years. Our stone house has very shallow foundations however, although it is built on rock so not a problem structurally, it means a root cellar here is out of the question!

Hi Nancy,

The land around is totally, utterly flat!

Yeah, that's what I was worried about with digging a pit - it seems like it would be impossible to ever clean out properly.

The barn floor is already sunk down about half a foot to a foot in places (it currently has a lot of dirt and soil piled in one end that needs removing), but yes with the mezzanine on top if we dug it out a bit more then it does become basement-like, although the door opens to ground level.

Making a test excavation is a good idea though - perhaps when we clear the soil and rubble it will be deeper than it seems at first glance! I think this will be my first step.

I can't build up because we literally just finished having a new roof put on it today with panel sandwich insulation and terracotta tiles on top... so that's that really! We couldn't make the walls any higher than they were originally due to building regulations.

Jay Angler wrote:I'm going to throw a few ideas and maybe some will either stick, or generate even better ideas:

1. What is the slope of the roof? Could you build a mezzanine level across only at the tallest part of the roof, as a compromise?

2. Do you need a continuous mezzanine? Could you build sections of mezzanine, with gaps, so while clearing the bedding, you can be standing in a open area, but be reaching into a low area?

3. Considering your concern about undermining the foundation, have you considered digging out the floor further, but leaving 2 ft or so at its current depth all around the edge? Consider some kind of shoring (rock, old breeze blocks or a rot-resistant wood come to mind), to make sure the edge doesn't collapse over time. Again, the main part of the floor will be closer to head height, but you can reach with tools the area that is raised.

4. The step down is already considerable for humans. If you're going to be cleaning this out with a wheelbarrow, I would consider making a ramp in. At the very least, I would  be thinking hard about how to access both levels safely and for the things you need to use them for. Ramps take up a lot of space, so stairs might be better so long as you put a block and tackle in to raise and lower loads of things.

1. This is complicated, but half the roof is sloped, above the hayloft. The other half (above the potential mezzanine) is flat. I've attached a new diagram. Coloured lines show potential mezzanine heights.

2.I like the idea of building a mezzanine floor that is like 'crinkle-cut' with some sections higher than others. Above and below will have goat beds or nests, so the crinklecut shape could be used to help accommodate these both above and below the mezzanine. I like this idea!

3. I did think of that but the building is not very big and it would reduce the floor space. This is definitely a possibility though. I know the goats would definitely enjoy jumping up and down off the raised bit!

4. It has a ramp made of dirt down from the door!

How much below the existing outside grade are you expecting the floor to be?

Since the land outside if flat your best option would be to dig a pit and put in a sump pump.  To pump the water out as needed.  

You should also make sure all rain water, run off and spillage from watering the animals is all directed away from the barn.  I would start with rain gutters and make sure the land all around the barn slightly slopes away from it and move any water troughs out and away from the barn.

I would be very worried about digging deeper and undermining the foundation.
My guess is you live somewhere that freezes.  The foundation should go below the frost level.  If you dig it out, everything may be fine as long as you keep animals and deep bedding in it to keep it warm-ish.  But if you ever let it go a winter empty there could be a chance the frost could below the footings on the inside and damage it.

How important is it that you can stand up fully?  Often when shoveling and sweeping a person hunches over and if the ceiling above is a bit low it isn't a problem.  Also make sure you are including the thickness of your future floor joists when doing your calculations.

J Hillman wrote:How much below the existing outside grade are you expecting the floor to be?

Since the land outside if flat your best option would be to dig a pit and put in a sump pump.  To pump the water out as needed.  

You should also make sure all rain water, run off and spillage from watering the animals is all directed away from the barn.  I would start with rain gutters and make sure the land all around the barn slightly slopes away from it and move any water troughs out and away from the barn.

I would be very worried about digging deeper and undermining the foundation.
My guess is you live somewhere that freezes.  The foundation should go below the frost level.  If you dig it out, everything may be fine as long as you keep animals and deep bedding in it to keep it warm-ish.  But if you ever let it go a winter empty there could be a chance the frost could below the footings on the inside and damage it.

How important is it that you can stand up fully?  Often when shoveling and sweeping a person hunches over and if the ceiling above is a bit low it isn't a problem.  Also make sure you are including the thickness of your future floor joists when doing your calculations.

Well, the floor is already sunken between 0.5 and 1 feet in places, but it would have to go deeper in relation to the height we build the mezzanine at! Probably at least another foot if we wanted to be able to stand on the mezzanine.

A pump is out of our price range and area of expertise as this barn has no electricity and we lack the skills/funds to do that sadly.

It definitely has gutters and I'll be directing rain runoff into a small ditch that leads into the orchard. I can't do major landscaping around the barn though as the property is totally inaccessible to things like diggers, tractors etc. It would also probably mess up the little goat pen that we've built around the barn.

Luckily I don't think it freezes here beyond a hard frost forming a crust at the surface of the soil. We do intend to keep goats for the foreseeable future., hopefully forever as we really love them!

My partner is 6'2" and really wants to be able stand up there... I am shorter - it honestly wouldn't be so much of a problem if it were just me! We do spend a lot of time down in the goat house though, trimming hooves, taking temperatures to monitor health, etc. - and giving instructions/demonstrations to volunteers about goat care so they can learn.

I will definitely need to take the joists into account as well!

I also think Jay is onto something.
This sounds like a warehouse or bookstore situation, where the humans need more space to maneuver than the creatures or things they are tending to.
Goat stalls that can be cleaned without being entered could ring the ground floor and have a mezzanine over top of them.
That ring of mezzanine could have dove cages from floor to ceiling.
In the center of the barn, the mezzanine would be higher, to give headroom to people working below.
This section would be used for more cages, accessed and tended to by a person standing on the lower mezzanine.
The ground floor beneath can be used for access to the goats, but also for classes, etc.

As for drainage, digging deeper , etc, how old is this structure?
It has seemingly survived a long time, even without a good roof, so I would be inclined to leave the foundation alone for now.

Rudyard, your diagram would be more helpful for me, if you added at least approximate measurements.

The building is certainly much more complex than I thought. It is important that your changes don't interfere with long term safety - of the foundation and of people's heads!